All types of writing have specific stylistic features. Students commonly describe academic writing as formal because textbooks and journals often contain words, phrases and terminology that are uncommon in non-academic writing such as emails and journalism. Students often worry that they are not using sufficiently complex or difficult language, so they use words and terms that they don't really understand - this means they produce text about complex ideas and issues that is very difficult to understand. Try and write as simply and clearly as you can about a complex issue; use complex vocabulary and language structures because they are required to express an idea precisely, not to make your essay sound "more academic".